1. Technical Field
The present invention relates to an induction heating cooker for performing induction heating of an object to be heated such as a pan or a flying pan using an electromagnetic induction heating coil.
2. Background Art
In recent years, induction heating cookers for performing induction heating of an object to be heated such as a pan with a heating coil are recognized to have superior characteristics of being safe, clean, and highly efficient, and thus are widely used. An induction heating cooker of this type including an infrared sensor for detecting infrared energy radiated from the heated object to detect the temperature of the heated object has been proposed. The infrared sensor is provided at the lower side of a top plate, and receives the infrared light radiated from the heated object that enters from an infrared light incident region formed to transmit the infrared light in the top plate, and outputs a signal that changes according to the temperature of the heated object. The heating cookers described in Patent document 1 and Patent document 2 detect the temperature of the heated object using the infrared sensor, and performs heating control of the heating coil based on the detected temperature.
Patent document 1: JP-A-11-225881
Patent document 2: JP-A-2007-115420
FIG. 11 is a diagram showing a relationship between the temperature of a heated object and a generated radiation energy amount. A solid line 47 shows a case in which the heated object is a black body (reflectivity=1), and a broken line 48 shows a case in which the heated object is of a magnetic stainless steel (reflectivity=0.4). According to the figure, the radiation energy at the time when the temperature of the black body is 300° C. and the radiation energy at the time when the temperature of the magnetic stainless steel is 447° C. are substantially equal. Thus, the absolute value of the energy amount received by the infrared sensor greatly changes due to the difference in reflectivity of the heated objects. A large error occurs if the absolute temperature of the heated object is calculated based on the absolute value of the energy amount received by the infrared sensor.
In the heating cooker described in Patent document 1, the temperature of the heated object is converted from the amount of light received by the infrared sensor and the reflectivity of the heated object, and the temperature of the heated object is controlled based on the converted absolute temperature information. In such a method, the reflectivity is measured and thus the configuration becomes complicated, or the reflectivity may not be accurately measured due to stain of the infrared light incident region or the heated object.
Patent document 2 proposes a heating cooker including an infrared detection means for measuring the temperature of the heated object without being subject to the influence of difference in the emissivity of the heated object by calculating the output ratio of infrared detection elements using the infrared detection elements made up of two Si photodiodes having a peak sensitivity smaller than or equal to 1 μm in different wavelength regions. However, two infrared detection elements are necessary and thus the configuration becomes complicated, which are susceptible to the influence of disturbance light.
In view of solving the above problems, the present invention aims to provide an induction heating cooker that is less susceptible to disturbance light and stain of the top plate and the object to be heated, and is capable of performing the temperature control of the object to be heated by an infrared sensor with a simple configuration.